我们研究了普适跷跷板模型的CP破坏，特别是它的夸克扇区。该模型基于SU（2）_L \times SU（2）_R \times U（1）_{Y^ \prime }.为了计算夸克扇区中参数的个数，我们利用了弱基变换的自由度。对于N（3）代模型，夸克扇区中CP破坏相的数目被确定为3N^2- 3 N +1（19）。我们还构造了三代普适跷跷板模型中Yukawa耦合矩阵和SU（2）单重夸克质量矩阵的19个CP破坏弱基不变量。给出了中性流诱导的夸克相互作用项的精确公式。通过寻找弱基到质量基的变换，将带电电流和中性电流都用质量基表示。最后，在SU（2）R破缺尺度vR远大于电弱破缺尺度vL的条件下，近似计算了混合矩阵元。
英文摘要：
We study the CP violation of universal seesaw model, especially its quark sector. The model is based on SU(2)_L \times SU(2)_R \times U(1)_{Y^\prime}. In order to count the number of parameters in quark sector, we use the degree of freedom of weak basis transformation. For N(3)-generation model, the number of CP violating phase in quark sector is identified as 3N^2-3N+1 (19). We also construct nineteen CP violating weak basis invariants of Yukawa coupling matrices and SU(2) singlet quark mass matrices in the three-generation universal seesaw model. The quark interaction terms induced by neutral currents are given as an exact formula. Both of the charged current and the neutral current are expressed in terms of the mass basis by finding the transformations from weak basis to mass basis. Finally, we calculate the mixing matrix element approximately assuming that the SU(2)_R breaking scale v_R is much larger than the electro-weak breaking scale v_L.
We discuss the minimal seesaw model for the Dirac CP violating phase of the lepton mixing matrix. We introduce two right-handed Majorana neutrinos and obtain several textures of the tri-maximal lepton mixing matrices. Moreover, we discuss the observed baryon asymmetry of the universe through the leptogenesis mechanism. As the result, we obtain the specific model which predicts the negative sign of maximal Dirac CP violating phase and normal hierarchy of neutrino masses.
Type I Seesaw Mechanism, Lepton Flavour Violation and Higgs Decays
我们回顾和更新目前的唯象约束的最小I型跷跷板扩展的标准模型，其中新物理的内容可以在电弱尺度探测。在这类模型中，中微子Yukawa耦合的味结构由再现中微子振荡数据的要求决定。对跷跷板参数空间的最强约束是最近μ -> e γ衰变率的上限。非标准的希格斯玻色子玻色子衰变为轻中微子和重中微子的过程也可能提供对这些跷跷板情景的独立测试。
Upcoming Lepton Flavour Violation experiments searching for $μ\rightarrow 3e$ and $μ$ to $ e $ conversion in nuclei processes will provide new opportunities to test the fundamental properties of the neutrino sector, and possibly the origin of matter. In recent work, it was shown that the Type II Seesaw mechanism alone can simultaneously explain the neutrino masses, Leptogenesis, and inflation. A key prediction of this model was the possibility of signals being produced in Lepton Flavour Violation decays. Searches at future experiments such as Mu3e and COMET will be integral to determining the …
The seesaw mechanism explains the exclusive smallness of neutrino masses by the presence of very heavy Majorana masses and leads to the appearance of Majorana particles and to the direct lepton number violation. The author proposes a seesaw scenario that produces only Dirac neutrinos with the same violation. This scenario appears possible for heavy neutrinos with non-perturbative Higgs boson H couplings. Such a scenario could be accomplished in the model describing the structure of weak mixing matrices for quarks and leptons through the existence of very heavy mirror analogs of Standard Model …
Supersymmetric Seesaw without Singlet Neutrinos: Neutrino Masses and Lepton-Flavour Violation
我们考虑了由重SU（2）_W三重态而不是“右手”中微子单线态交换引起的超对称跷跷板机制产生中微子质量。我们表明，在这种情况下，在低能量的大气和太阳中微子实验中测试的中微子味结构是直接继承的中微子汤川耦合的三胞胎。这使我们能够预测τ--> μ γ（或τ--> e γ）和μ--> e γ衰变率的比率，根据低能中微子参数。此外，一旦模型被嵌入到大统一模型中，夸克味破坏就可以与轻子味破坏联系起来。
We propose simple scoto-seesaw models to account for dark matter and neutrino masses with spontaneous CP violation. This is achieved with a single horizontal $\mathcal{Z}_8$ discrete symmetry, broken to a residual $\mathcal{Z}_2$ subgroup responsible for stabilizing dark matter. CP is broken spontaneously via the complex vacuum expectation value of a scalar singlet, inducing leptonic CP-violating effects. We find that the imposed $\mathcal{Z}_8$ symmetry pushes the values of the Dirac CP phase and the lightest neutrino mass to ranges already probed by ongoing experiments, so that normal-ordere…
Lepton flavor violation and non-unitary lepton mixing in low-scale type-I seesaw
在低尺度的跷跷板机制中，例如逆跷跷板和线性跷跷板，人们期望（i）潜在的大轻子味破坏（LFV）和（ii）相当大的非标准中微子相互作用（NSI）。我们考虑轻子混合矩阵中的非么正效应的大小之间的相互作用，以及实验室中LFV搜索的约束条件。我们发现，NSI参数可以是相当大的，在某些情况下高达百分比水平，而LFV率，如μ-> e γ，位于当前的限制，包括最近由MEG合作组设置。因此，即将到来的长基线中微子实验为补充LFV和弱普适性测试提供了一个机会窗口。
We discuss the correlation between the CP violating Dirac phase of the lepton mixing matrix and the cosmological baryon asymmetry based on the leptogenesis in the minimal seesaw model with two right-handed Majorana neutrinos and the trimaximal mixing for neutrino flavors. The sign of the CP violating Dirac phase at low energy is fixed by the observed cosmological baryon asymmetry since there is only one phase parameter in the model. According to the recent T2K and NO$ν$A data of the CP violation, the Dirac neutrino mass matrix of our model is fixed only for the normal hierarchy of neutrino mas…
Neutrino are massless in the Standard Model. The most popular mechanism to generate neutrino masses are the type I and type II seesaw, where right-handed neutrinos and a scalar triplet are augmented to the Standard Model, respectively. In this work, we discuss a model where a type I + II seesaw mechanism naturally arises via spontaneous symmetry breaking of an enlarged gauge group. Lepton flavor violation is a common feature in such setup and for this reason, we compute the model contribution to the $μ\rightarrow eγ$ and $μ\rightarrow 3e$ decays. Moreover, we explore the connection between the…
Motivated by the recently reported measurement of the $W$ boson mass $M_W = 80.4335 \pm 0.0094$ GeV by the CDF collaboration, we propose a type III seesaw extension of the minimal supersymmetric standard model (MSSM) which also includes an R-parity violating term. Without taking potential SUSY radiative corrections into account, we show that the CDF measurement of $M_W$ and the LEP measurement of the $ρ$ parameter can be simultaneously accommodated at the $2 σ$ level. A long-lived gravitino in a few GeV mass range is a unique viable dark matter candidate in this framework.
We present a study of resonant leptogenesis in a radiative seesaw model. We consider the case where two quasi-degenerate right-handed neutrinos realize resonant leptogenesis, and the CP violation necessary to achieve leptogenesis occurs through the CP phases present in the neutrino mixing matrix. A numerical analysis is performed by taking the best-fit values from the current global data for three neutrino mixing angles and two mass-squared differences. We have shown how the predicted value of baryon asymmetry depends on the Dirac and Majorana CP phases. With the particular choice for the mass…
Given its briefness and predictability, the minimal seesaw -- a simplified version of the canonical seesaw mechanism with only two right-handed neutrino fields -- has been studied in depth and from many perspectives, and now it is being pushed close to a position of directly facing experimental tests. This article is intended to provide an up-to-date review of various phenomenological aspects of the minimal seesaw and its associated leptogenesis mechanism in neutrino physics and cosmology. Our focus is on possible flavor structures of such benchmark seesaw and leptogenesis scenarios and confro…
Charged Lepton Flavour Violation in Supersymmetric Low-Scale Seesaw Models
我们研究了最小超引力的低尺度跷跷板模型中的带电轻子味破坏，由于近似轻子数对称性，该模型实现了大的中微子汤川耦合。在这样的模型中有两个主要的轻子味破坏源。第一个来源来自通常的软超对称性破坏部门，而第二个是完全超对称的，来自超对称中微子汤川部门。在最小超引力的框架下，我们考虑了轻子味破坏的软源和超对称源，并计算了一些可能的轻子味破坏跃迁，如μ子和τ子的光子衰变，μ-> e γ，τ-> e γ和τ-> μ γ，它们的无中微子三体衰变，μ-> e e e，τ-> e e e e e，τ-> mu mu，τ-> e e μ和τ-> e μ μ以及核内的相干μ-> e转换。在考虑到目前的轻子味违反实验的排斥界限，我们得出的通用重马约拉纳质量尺度mN和轻到重中微子混合的理论限制。超对称低尺度跷跷板模型提供了不同的相关预测轻子味违反签名，这可能会发现在当前和预计的实验，如MEG，彗星/棱镜，Mu 2 e，超级BELLE和LHCb。
我们在超对称反跷跷板模型的框架下研究中微子的质量。与非超对称的版本不同的是，仅用一对单态的最小实现就足以解释所有的中微子数据。我们计算的中微子质量矩阵的1-循环顺序，并显示如何中微子数据可以描述的模型参数。然后，我们计算率轻子味违反（LFV）的过程，如$μ\to e γ$，和电荷衰变到单重标量中微子。后一种衰变可能在LHC上观测到，并显示出由产生观测到的大中微子角的相同参数决定的特征衰变模式。
We study lepton flavor violation (LFV) within the Littlest Higgs Model with T parity (LHT) realizing an inverse seesaw (ISS) mechanism of type I. With respect to the traditional LHT, there appear new $\mathcal{O}$(\textcolor{black}{10} TeV) Majorana neutrinos, driving LFV. For $τ\to\ell\ell'\bar{\ell}"$ (including wrong-sign, $\ell=e, μ$) decays and $μ\to e$ conversion in Ti, we get typical rates only one order of magnitude below present bounds ($\ell\to\ell'γ$ can reach the current upper limit) and for $Z\to\barτ\ell$, $μ\to e e \bar{e}$ and conversion in Au, results are within two orders of …
